I hope someone can help I have a 5.4 expedition that codes a 402, I hate to buy a part that may not be the problem so Im asking for help. I have already replaced most all vacuum lines under the hood and I think it may be the EGR sensor what do the experts think?

Thanks

 

The DPFE sensor (controls EGR) might be bad. If you have a scanner, you might be able to check the voltage at the DPFE. I'm not positive but, I think,
if the voltage at the sensor is low, then the DPFE is bad.

Hope this helps
Mike

 

Again, the DPFE doesnot control the EGR.
The 402 code indicates the EGR valve is allowing to much exhaust flow either because it is stuck off it's seat or the vacuum control valve is allowing vacuum to the valve when not requested by the PCM computer.

The DPFE is a test sensor only and does not directly control anything. It is there to test flow only and that is what it has done to report the 402 code.
The PCM is the controller of all events.

On the older cars before 96, an EVP was mounted on the EGR to report EGR malfunction.

 

How many miles? Hows the truck running? Exactly right on the DPFE summary, but it can malfunction.

 

If you take your truck to a Ford dealer, they will immediately replace the DPFE sensor on your truck as soon as they have that code (along with several others). That's how crappy these sensors were and Ford knows it.

I'd suggest the same in this case.

Steve

 

I did replace the sensor and cleaned the throttle body it runs fine, I think the sensor might give the engine a false read, because I didnt do anything to the EGR valve itself.

I hope this helps others and thanks to all who advised.

 

No prob, thanx for letting us know that was the problem.

 

get an EGR reducer... they sell em on ebay if ur gettin to much flow restrict it... lol j/k that will set off another code.. just that the damn IAC restrictor plates that will destroy your engine after a few thousand miles.. by forcing blowby.. throughthe PCV